1. Field of the Invention
The present invention relates to a small size zoom lens system, and an image pickup apparatus such as a compact digital camera in which the small size zoom lens system is used.
2. Description of the Related Art
In an image pickup apparatus such as a digital camera and a video camera, a high image quality and a high zooming ratio have hitherto been sought. For example, in Japanese Patent Application Laid-open Publication No. 2006-39523, a three-unit zoom lens system which includes in order from an object side thereof, a first lens unit having a positive refracting power, a second lens unit having a negative refracting power, and a third lens unit having a positive refracting power has been disclosed. This three-unit zoom lens system achieves a zooming ratio of about 2.9. Moreover, the second lens unit is a cemented lens formed by a positive lens, a negative lens, and a positive lens in order from the object side, and secures optical performance and reduces an effect due to decentering.